Sighting System: SightMaster Lensatic is equipped with a great parallax free glass lens magnification ( 10x ) sighting system in aluminium housing. SightMaster Prismatic is equipped with a open light , parallax free prismatic magnification ( 10x ) sighting system, on top of the aluminium housing. Capsule: Anti static liquid filled for optimal dampening of the compass card. Compass card: SightMaster Lensatic is equipped with the aluminium compass with precision scale and SightMaster Prismatic is equipped with a transparent compass card with precision scale and both models are equipped with a top scale for direct readings on the top of the capsule at the lubber line. Sapphire jewel bearing for friction free movement of the card allowing fast and accurate readings. Accuracy: Max + - 0.5° from true magnetic course with precision sighting. Max + -1.0 ° from true magnetic course with direct reading at the lubber line on top of the capsule.